This invention relates to lock assemblies, and more particularly to a dead bolt lock assembly particularly adapted for use with a flight deck door in an aircraft.
Recent events have made increased security in the cockpit of a commercial airliner an important consideration. More specifically, these recent evens have led to new government requirements for lock assemblies used on flight deck doors in commercial aircraft which provide an even greater degree of security to occupants in the flight deck area of the aircraft.
Traditionally, locking systems used on flight deck doors have involved the use of a lock assembly which may be unlocked with a key by a flight attendant or other member of the flight crew. However, if the key is obtained by an individual who is not authorized to enter the flight deck area, then such an individual would be able to unlock the door lock assembly and gain unauthorized entry onto the flight deck of the aircraft.
Accordingly, the need has arisen for a door lock assembly particularly well adapted for use with a flight deck door in an aircraft which enables the door lock assembly to be locked and unlocked with a key, but which also provides members on the flight deck the means to override or xe2x80x9clock outxe2x80x9d the assembly such that the assembly cannot be unlocked even with a key. In this manner, if members of the flight deck learn that an unauthorized individual on the aircraft may have obtained the key to the lock assembly, the lock assembly can be locked out from the flight deck side of the flight deck door, thereby preventing unlocking of the door lock assembly and unauthorized entry by an individual in the passenger cabin area. Such a door lock assembly would ensure that the occupants of the flight deck have the capability to prevent unlocking of the door lock assembly in the event of an in flight disturbance where it is deemed necessary to prevent any access whatsoever to the flight deck area by individuals in the passenger cabin area.
The above and other objects are provided by a door lock assembly in accordance with preferred embodiments of the present invention. The door lock assembly generally comprises a housing, a lock cylinder, a slide member, a dead bolt member and a lockout member. The lock cylinder is secured to the housing and includes a driver which is rotated when the proper key is inserted into the lock cylinder and rotated. The slide member is disposed such that it is able to engage a portion of the dead bolt and be moved laterally within the housing by the lock driver when the lock driver is rotated via the key. Thus, the key can be used to move the dead bolt member between a locked position, wherein it is engaged in a door jamb adjacent an edge of the flight deck door, or retracted into an unlocked position. The lockout handle is operatively secured to the slider member and is accessible from the flight deck side of the flight deck door by a crew member present in the flight deck area. In a first position, the lockout handle has no affect on operation of the dead bolt member via the key. Thus, when the lockout handle is in the first position, the dead bolt can be moved between its locked and unlocked positions simply by inserting the key into the lock cylinder and rotating the key between locked and unlocked positions. However, when the lockout handle is moved into a second position, the slider member is placed from the driver such that use of the key will not be able to unlock the dead bolt from its locked position. With the lockout handle in its lock out position (i.e., second position), the lock cylinder rotates but the driver does not make contact with the dead bolt member. Moving the lockout handle back into its first position displaces the slide member back into operative engagement with the lock driver, thus allowing the key to unlock the dead bolt member.
In one preferred form, the lock assembly of the present invention includes an escutcheon having a first camming surface. The lockout handle includes a second camming surface disposed in engagement with the first camming surface when the lock assembly is fully assembled. Movement of the lockout handle from the first position to the second position affects a camming action between the two camming surfaces which urges the lockout handle away from the door, thus displacing the slider out of operative engagement with the lock driver. In a preferred embodiment, a lock handle is also included and is operatively coupled to a handle driver member. When the dead bolt member is moved into its locked position by use of the key, the handle driver member is rotated, thus moving the lock handle simultaneously rotationally from a first position into a second position and thus indicating to individuals occupying the flight deck that the apparatus is in a locked position. In this preferred embodiment, the lock handle is disposed between the escutcheon and the lockout handle. Both of the handle members can be rotated when the lockout handle is also in its second position by a user grasping both handles with a single hand and rotating same.
The apparatus of the present invention thus provides a means for allowing members occupying the flight deck area of an aircraft to positively lockout the apparatus, thus preventing the apparatus from being unlocked in the event an unauthorized individual should gain access to the key. Advantageously, the apparatus allows an individual in the flight deck area to quickly and easily place the apparatus back into a condition wherein the key can be used to unlock the dead bolt. The apparatus provides an additional degree of security to the occupants of the flight deck by allowing them to place the apparatus in a condition wherein the apparatus cannot be unlocked even with the key.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limited the scope of the invention.